diff options
| -rw-r--r-- | doc/filters.texi | 10 | ||||
| -rw-r--r-- | libavfilter/version.h | 2 | ||||
| -rw-r--r-- | libavfilter/vf_drawtext.c | 22 |
3 files changed, 33 insertions, 1 deletions
diff --git a/doc/filters.texi b/doc/filters.texi index 99654ebcfb..f3e86c1693 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -2075,6 +2075,16 @@ The following functions are available: @table @command +@item expr, e +The expression evaluation result. + +It must take one argument specifying the expression to be evaluated, +which accepts the same constants and functions as the @var{x} and +@var{y} values. Note that not all constants should be used, for +example the text size is not known when evaluating the expression, so +the constants @var{text_w} and @var{text_h} will have an undefined +value. + @item gmtime The time at which the filter is running, expressed in UTC. It can accept an argument: a strftime() format string. diff --git a/libavfilter/version.h b/libavfilter/version.h index 04ab662660..64e1f4b4cc 100644 --- a/libavfilter/version.h +++ b/libavfilter/version.h @@ -30,7 +30,7 @@ #define LIBAVFILTER_VERSION_MAJOR 3 #define LIBAVFILTER_VERSION_MINOR 23 -#define LIBAVFILTER_VERSION_MICRO 103 +#define LIBAVFILTER_VERSION_MICRO 104 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \ LIBAVFILTER_VERSION_MINOR, \ diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c index 96512ab390..509fbd22f5 100644 --- a/libavfilter/vf_drawtext.c +++ b/libavfilter/vf_drawtext.c @@ -643,12 +643,34 @@ static int func_strftime(AVFilterContext *ctx, AVBPrint *bp, return 0; } +static int func_eval_expr(AVFilterContext *ctx, AVBPrint *bp, + char *fct, unsigned argc, char **argv, int tag) +{ + DrawTextContext *dtext = ctx->priv; + double res; + int ret; + + ret = av_expr_parse_and_eval(&res, argv[0], var_names, dtext->var_values, + NULL, NULL, fun2_names, fun2, + &dtext->prng, 0, ctx); + if (ret < 0) + av_log(ctx, AV_LOG_ERROR, + "Expression '%s' for the expr text expansion function is not valid\n", + argv[0]); + else + av_bprintf(bp, "%f", res); + + return ret; +} + static const struct drawtext_function { const char *name; unsigned argc_min, argc_max; int tag; /** opaque argument to func */ int (*func)(AVFilterContext *, AVBPrint *, char *, unsigned, char **, int); } functions[] = { + { "expr", 1, 1, 0, func_eval_expr }, + { "e", 1, 1, 0, func_eval_expr }, { "pts", 0, 0, 0, func_pts }, { "gmtime", 0, 1, 'G', func_strftime }, { "localtime", 0, 1, 'L', func_strftime }, |